Determination and pharmacokinetic study of 1-p-(3.3-dimethyl-1-triazeno) benzoic acid in cancer patients by capillary gas chromatography.

A capillary gas chromatographic method was developed for determining 1-p-(3.3-dimethyl-1-triazeno) benzoic acid in the plasma and urine of cancer patients under pharmacokinetic study. The drug was extracted with ethyl acetate and methylated with diazomethane. Octadelane (10 microg/ml) was added as internal standard. The separation was carried out on an OV-1 quartz capillary column, 15 m x 0.32 mm (0.52 microm), with high-purity nitrogen as carrier gas and flame ionization detector (FID) as detector. The column temperature was held at 130 degrees C for 9 min and then programmed to 240 degrees C, at a rate of 35 degrees C/min. The temperature of both injector and detector was 260 degrees C. The standard curve was linear from 0.4 to 40 microg/mL in plasma, and from 0.8 to 20 microg/mL in urine, with correlation coefficients of 0.9979 and 0.9932. The relative standard deviations (RSD) were less than 9.7%. The minimum recovery of this method was 81.8%. This method was applied to the pharmacokinetic studies of 1-p-(3.3-dimethyl-1-triazeno) benzoic acid in cancer patients after a single dose (i.v.) of 160, 420 or 760 mg/m(2) was administered. They all conformed to the two-compartment open model and showed linear pharmacokinetics. The excretion of this drug in the urine was minimal.